This invention relates to a hydraulic apparatus, and in particular, to an apparatus for protecting a hydraulic motor from motor outlet overpressurization.
Hydraulic motors are typically lubricated internally by leakage of highly pressurized hydraulic fluid. This lube leakage flow must be drained. One way to drain the lube leakage flow is to provide a separate motor case drain line. However, in situations where the motor is remote from the hydraulic power supply, an additional drain line may be undesirable. Another way to drain the lube flow is to reroute it with the motor return flow from the motor outlet. But, in this case, overpressurization of the return line can cause motor case seal failure. Accordingly, it would be desirable to provide a device for preventing such seal failure while still routing lube drain flow with the motor return flow.